What steps will reproduce the problem?
1. Added a bookmark to a Collection
2. Deleted bookmarked work
3. Error 500 displayed when mod of Collection attempts to access 'Approved Works' page
in 'Manage Items' and when the user who bookmarked the work tries to access theirs

Also if you add the bookmark of that deleted work to a moderated Collection, the Awaiting Approval page errors when the mod tries to access it. (The bookmark does not appear on the bookmarking user's Awaiting Approval page, so no errors occur.)

What is the expected output? What do you see instead?
Expected to be able to see my Approved Items page with the usual "this item has been
deleted" bookmark blurb on it. Instead got Error 500.

I can replicate this error in Chrome (v29.0.1547.76), Safari (v6.0.5 (8536.30.1)),
and Firefox (v17.0.1). Have not tested on other browsers.

Also tested a) adding a bookmark to the collection, rejecting said bookmark, and then
deleting the work that was bookmarked, and b) submitting a work to a moderated collection,
and then deleting that work. No problems with both.